As a laser oscillator, a laser oscillator having a structure in which a waveguide is formed by disposing upper and lower electrodes facing each other in an airtight container in which a laser medium gas is sealed and plasma discharge is generated between the electrodes has been known. In the laser oscillator with this structure, the plasma discharge causes an electronic state of an atom in gas to be excited, and optical resonation is caused by the reflection mirrors arranged at each end of the electrodes. A laser beam based on the optical resonation is configured to be extracted outside a window. Accordingly, in a case where a direction of the reflection mirror is not properly adjusted, stability of laser output and a position of a laser beam may be deteriorated.
In a conventional laser oscillator, as disclosed in Japanese Patent Application Laid-Open Publication No. 2002-84021 (Patent Document 1) and U.S. Pat. No. 5,140,606 (Patent Document 2), for example, a pan-tilt motion mechanism making each reflection mirror move left or right and up or down by a deformable thin plate and tension of a screw is configured at both ends of a housing of the laser oscillator, and a direction of each of the reflection mirrors is adjusted. In such attachment structure of the reflection mirror, the pan-tilt motion mechanism becomes complicated, and in order to cool heat of the reflection mirror generated by making a laser beam reflect, the attachment structure needs to be specially devised.